1975 evinrude 25 idle speed?

[acabtp]

i did a carb job and link & sync on a new to me 1975 evinrude 25 hp which now runs nicely, but the idle stop is set way too low and allows the motor to die (below ~ 480 rpm). the service manual i have says that the idle speed will be listed in the appendix, but it's not. what should the idle rpm be set around for a 1975 evinrude 25 hp (22 cu in)?

also, the nylon idle stop screw on the bottom of the vertical throttle shaft bottoms out on the tensioning spring with 1/4" or more of play before the idle stop (so i can't set the idle higher with it right now). is is possible for the vertical and horizontal throttle shaft gears to be installed a tooth off? there seems to be some extra play in the throttle armature under the flywheel as well, but i can't really find any source of it other than play in the gears of the throttle linkages. thoughts?

thanks

 

[fireman57]

Just adjust the stop screw out to where you are pleased with the idle. You can also screw that way out and use the thumb wheel on the throttle cable to set it where you want it and then turn the stop screw in where you are happy with the idle.

 

[acabtp]

Just adjust the stop screw out to where you are pleased with the idle.

Being a fisherman, I would run it at as low an idle as I could for trolling, but I don't want to run the risk of the water pump being run too slowly for adequate cooling, etc. I would rather just know what the recommended RPM was from the factory.

Also, it sounds like you are recommending adjusting a carb idle stop screw; that's not how it works on this model. The idle speed adjustment screw is on the bottom of one of the throttle shafts (sticks out below the lower cowl), and it is supposed to limit the throttle armature movement. But the adjustment screw on my outboard runs out of travel well before being able to adjust the idle up. The throttle plate in the carb closes when it is supposed to (between the indexing marks on the throttle cam).

You can also screw that way out and use the thumb wheel on the throttle cable to set it where you want it and then turn the stop screw in where you are happy with the idle.

I appreciate the help, but really think you must be thinking of a different set up. There are no throttle cables on this motor, it's all shafts, gears and linkages.

I'll go take some pictures or a video to better illustrate the situation.

 

[AlTn]

I currently have an 18 and 25 hp. both 1971 models, both have the idle adjustment screw setup you describe. Both original adjustment screws have been replaced by machine screws < prior owners >. 1 screw is 1 1/4 " long the other is 2". Soooo, I'd suggest that you just take your adjustment screw with you to the hardware store and buy one that's longer and will provide some adjustment for the idle stop. As to the idle speed setting...generally....motor at operating temp., in gear pushing the boat ~750 rpm.

 

[acabtp]

I currently have an 18 and 25 hp. both 1971 models, both have the idle adjustment screw setup you describe. Both original adjustment screws have been replaced by machine screws < prior owners >. 1 screw is 1 1/4 " long the other is 2". Soooo, I'd suggest that you just take your adjustment screw with you to the hardware store and buy one that's longer and will provide some adjustment for the idle stop. As to the idle speed setting...generally....motor at operating temp., in gear pushing the boat ~750 rpm.

great, thank you kindly

 

[fireman57]

My bad. You have the throttle linkage that attaches to the engine outside the cover if I remember correctly. There should be a big plastic screw that you can turn in or out for more or less idle.